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Background
Prostate cancer (PCa) is the most common solid organ malignancy amongst men and the second leading cause of cancer related death; however, it is the only tumor that is diagnosed by a non-targeted sampling method. Furthermore, the United States Preventative Task Force classified PSA-based PCa screening Grade D to prevent over-diagnosis and over treatment given the inability to effectively screen patients who would benefit from treatment. However, MRI has been suggested as an alternative to US given its increased resolution, functional assessment, superior anatomical imaging, and assessment of extra-prostatic involvement. An office-based MRI-USG fusion platform has been developed to target biopsies of suspicious lesions identified on MRI in addition to systematic biopsies. We sought to provide the initial report of fusion biopsy cancer detection rates in a first-time prostate biopsy population.
Methods
Consecutive patients underwent MRI-USG fusion prostate biopsy for elevated PSA, abnormal digital rectal exam, or prior negative biopsy with a persistently elevated PSA. All subjects underwent pre-biopsy multi-parametric MRI (MP-MRI) at 3.0T. A unique distinction from the current published data is the MP-MRI was done without an endorectal coil, which causes significant discomfort to the patient. Lesions visible on MRI were outlines in 3 dimensions and assigned increasing cancer suspicion levels (low, moderate, high) by a radiologist. The ArtmeisTM biopsy tracking system was used to fuse the stored MR images with real-time ultrasound generating a 3D prostate model with both a 12-core systematic template map and real-time visualization of MR-identified lesions. Using the 3D model, systematic and targeted (if present on MRI) biopsies were performed by a single urologist (PS) in an office setting under local anesthesia.
Results
A total of 60 patients (mean age 65yrs, median PSA 6.8) underwent MRI and biopsy between December 2012 and September 2013. 28 (47%) patients (median PSA 5.8, mean age 67.2yrs) had no prior prostate biopsy. In this group, prostate cancer was detected in 18(64%) patients, with 15(83%) of those considered clinically significant (Gleason score ≥7).  24(86%) patients had a lesion visible on MRI, targeted biopsy detected cancer in 15 (63%), and 13(87%) of these cancers were clinically significant. Systematic biopsies detected 14 cancers, with clinically significant disease in 10(71%).  Twenty patients had moderate or high suspicion lesions on MRI evaluation, and cancer was detected in 12 (60%) of these patients; 100% of the detected cancers were clinically significant (Gleason 7 to 9).  11/18 (61%) patients had cancer detected on both systematic and targeted biopsy. 4 patients only had cancer detected on targeted biopsy, three of which were clinically significant disease.

Conclusion
MRI-USG fusion targeted biopsy has been associated with high detection of both prostate cancer and clinically significant prostate cancer which has been described to be twice the rate of systematic trans-rectal ultrasound guided biopsy. This data supports the use of MRI-USG fusion targeted biopsy for the first time prostate biopsy population by improving cancer detection.